Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1997FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)TRANSMISSIONAUTOMATIC TRANSAUTOMATIC TRANSMISSION DIAGNOSIS - 4L80-E (2-DIGIT CODES)
1997 Chevrolet Forward Control 5.7 R, Automatic
Automatic Transmission Diagnosis - 4L80-E (2-Digit Codes)
1997 Chevrolet Forward Control 5.7 R, AutomaticSECTION Automatic Transmission Diagnosis - 4L80-E (2-Digit Codes)
- Application
- Description
- Operation
- Electronic Self-Diagnostics
- Clutch & Band Application
- Diagnostic Tests
- Notes
- Automatic Transmission Diagnosis - 4L80-E (2-Digit Codes)
- On-Board Diagnostic (OBD) System Check
- No Malfunction Indicator Light (Mil)
- No Data Link Connector Data
- DTC 21: TP Sensor Signal Voltage High, Or DTC 22: TP Sensor Signal Voltage Low (6.5L VIN Y - L57 Only)
- DTC 24: Output Shaft Speed (OSS) Sensor Circuit Low
- DTC 28: Transmission Fluid Pressure (TFP) Position Switch
- DTC 37: TCC Brake Switch Stuck On, Or DTC 38: TCC Brake Switch Stuck Off
- DTC 39: Torque Converter Clutch (TCC) Stuck Off
- DTC 52: System Voltage High Long, Or DTC 53: System Voltage High
- DTC 58: Transmission Fluid Temperature (TFT) Sensor Circuit Low
- DTC 59: Transmission Fluid Temperature (TFT) Sensor Circuit High
- DTC 63: BARO Sensor Circuit High, Or DTC 64: BARO Sensor Circuit Low (6.5L VIN Y - L57 Only)
- DTC 68: Transmission Component Slipping
- DTC 69: Torque Converter Clutch (TCC) Stuck On
- DTC 71: Camshaft Position (CMP) Sensor Circuit Low (6.5L VIN Y - L57 Only)
- DTC 72: Output Shaft Speed (OSS) Sensor Circuit Loss
- DTC 73: Pressure Control Solenoid (PCS) Circuit Error
- DTC 74: Input Shaft Speed (ISS) Sensor Circuit Error
- DTC 75: System Voltage Low
- DTC 79: Transmission Fluid OVERTEMPERATURE
- DTC 81: 2-3 Shift Solenoid Circuit Fault
- DTC 82: 1-2 Shift Solenoid Circuit Fault
- DTC 83: TCC PWM Solenoid Circuit Fault
- DTC 85: Undefined Gear Ratio
- DTC 86: Low Ratio Error
- DTC 87: High Ratio Error
- Electronic Testing
- Wiring Diagrams
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.